title: Enterotoxigenic Escherichia coli modulates host intestinal cell membrane asymmetry and metabolic activity.
abstract: Enterotoxigenic Escherichia coli (ETEC) is a common cause of travelers' and postweaning diarrhea in humans and swine, respectively. The extent to which ETEC damages host cells is unclear. Experiments are presented that probe the ability of porcine ETEC isolates to induce apoptosis and cell death in porcine intestinal epithelial cells. Quantification of host phosphatidylserine exposure following ETEC infection suggested that ETEC induced changes in plasma membrane asymmetry, independent of the expression of the heat-labile enterotoxin. Significant host cell death was not observed. ETEC infection also caused a drastic inhibition of host esterase activity, as measured by calcein fluorescence. While ETEC infection resulted in activation of host caspase 3, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling of DNA double-strand breakage, indicative of late stages of apoptosis, was not observed. Camptothecin-induced apoptosis markedly increased subsequent ETEC adherence. Transfer of cell-free supernatants from apoptotic cells to bacterial inocula prior to infection of naïve cells increased the transcriptional activity of the regulatory region upstream of the K88ac operon and promoted subsequent adherence to host cells.
authors.affiliation: Center for Infectious Disease Research and Vaccinology, South Dakota State University, Brookings, South Dakota 57007, USA.
authors.forename: Amber M
authors.initials: AM
authors.lastname: Johnson
authors.forename: Radhey S
authors.initials: RS
authors.lastname: Kaushik
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Rotella
authors.forename: Philip R
authors.initials: PR
authors.lastname: Hardwidge
mesh_terms: D000818:Animals; D017209:Apoptosis; D001422:Bacterial Adhesion; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism*; D054307:Enterotoxigenic Escherichia coli / Q000502:physiology*; D004847:Epithelial Cells / Q000382:microbiology*; D004950:Esterases / Q000378:metabolism; D007413:Intestinal Mucosa / Q000382:microbiology*; D010718:Phosphatidylserines / Q000032:analysis; D013552:Swine
chemical_list: D010718:Phosphatidylserines; D004950:Esterases; D053148:Caspase 3